NASA's Spacecraft Propulsion Research Facility (B-2) is the world's only facility capable of testing full-scale upper-stage launch vehicles and rocket engines under simulated high-altitude conditions. The engine or vehicle can be exposed for indefinite periods to low ambient pressures, low-background temperatures, and dynamic solar heating, simulating the environment the hardware will encounter during orbital or interplanetary travel.

Vehicle engines producing up to 400,000-lb of thrust can be fired for either single or multiple burn missions, utilizing either cyrogenic or storable fuels or oxidizers. Engine exhaust conditions can be controlled to simulate a launch ascent profile. In addition, conditions can be maintained before, during, and after the test firing. B-2 offers a complete "test-as-you-fly" environment to thoroughly ground test flight hardware and reduce the likelihood of costly flight failures. In 1998, tests of the Boeing Delta III cryogenic upperstage were successfully conducted in the B-2 facility.

During a typical test program, the test article is installed within the B-2 vacuum chamber and the necessary electrical power, fuel, oxidizer, and purge gas connections are made. The low-pressure, temperature-controlled flight environment is established to thermally condition the hardware and propellants prior to engine firing.

A Programmable Logic Controller conducts all events of the engine test firing from the start of the water deluge system until the completion of the engine test firing and facility shutdown. An abort system provides monitoring through the test period of both facility and test parameters. Test-firing periods extending up to 880 s (14 min) can be accomodated. Multiple test firings and thermal conditioning periods can be conducted to fully simulate the actual flight scenario.